The following invention relates to a product size grading system and more particularly to a system employing a roller table having a progressive speed transmission system and flexible nubbin rollers for sizing the product as it is conveyed across the roller table.
Size grading systems of the type that are used for sizing food product typically consist of vibratory conveyor screens having slots or holes of a predetermined size so that undesirably sized pieces of food product (such as those that are cut too short, slivers and fines) fall through the slots as the product is conveyed by vibratory action. The problem with such devices is that undesirable product pieces are not likely to fall through the slots or holes in the vibratory conveyor screen unless they are properly aligned. In theory, at least vibration eventually aligns these pieces over a slot or hole at some point during travel, but as a practical matter this does not always occur. In addition with such devices, product of the proper length may become oriented endwise up and unintentionally slip through the slots or holes. Also, curved or bent pieces of product will in most cases pass through screens or holes. Such product is, however, useful and the mis-sizing caused by the screen is wasteful. In addition, vibratory screens take up an inordinate amount of floor space and are noisy.
Conventional roller beds have also been employed in the past for removing fines and slivers but are inadequate for properly sizing product. Roller beds frequently employ angled rollers which can also mash or otherwise damage properly sized product.